A marathon is a 26.2 mile (42.2 km) race done over hill and dale at a pace that is typically less than 5 min per mile for the winner of the elite men’s division and just over 5 min per mile for the winner of the elite women’s division. The energy (ATP) required for such performances is derived from both aerobic (mitochondrial oxidative) and anaerobic (creatine phosphate and glycolysis) processes.

Oxidative processes obviously involve the use of oxygen in the metabolism of carbohydrates and fats in the mitochondria of the cell. How much fat do you think is used in such a race?

Given:

Male marathon runner
132 pounds
Time: 2hr:20min:00sec
Respiratory Exchange Ratio R = 0.90.

Must lookup:

RER to fat kcal conversion
Relative VO2 to absolute VO2 conversion
Absolute VO2 conversation to kcals
Grams of fat to lbs of fat conversion

Equation:

Oxygen cost of running: VO2 (ml. kg-1.min-1) = 0.2 ml O2.kg-1.m-1 x speed (m. min-1) + 3.5 [Note: the vertical component is removed - we assume it is a flat course]

Question:

How many pounds of fat did he use in his marathon run? (show all of your work)